1. Field of the Invention
The present invention relates generally to a multi-standard transceiver for supporting a plurality of time division duplexing wireless communication standards and, more particularly, a multi-standard transceiver for supporting IEEE 802.11b, IEEE 802.11g and High-speed Portable Internet in 2.3-2.4 GHz band.
2. Description of the Related Art
Recently, various communication standards are emerging to meet users' demands for various wireless communication services. In particular, as the use of the wired Internet is popularized, a variety of Wireless Local Area Network (WLAN) standards, such as IEEE 802.11b and IEEE 802.11g in 2.4 GHz band and IEEE 802.11a in 5 GHz band, are established to support broadband Internet access even in a wireless communication environment. A lot of users are already using WLAN service.
However, the above-described WLAN standards do not adequately guarantee users' mobility, so that users' demands for new wireless mobile Internet service are increasing. Correspondingly, in Korea, High-Speed Portable Internet (Hpi) in 2.3 GHz band has been proposed and will be established soon as a standard, which is based on Time Division Duplexing (TDD)/Orthogonal Frequency Division Multiplexing (OFDM). In regard to international standardization, the task group of IEEE 802.11e is standardizing portable Internet service that can guarantee mobility.
Meanwhile, even though the High-speed Portable Internet (HPi) service is launched, the HPi service may start from local areas. Accordingly, a problem is anticipated in that the users of the areas where HPi is not supported cannot help using the existing WLAN service. Accordingly, wireless Internet service can be used without inconvenience only when HPi Access Terminals (HPi-ATs) support both the HPi standard and the existing WLAN standards. This type of problem was already experienced when the cellular mobile communication (AMPS) was upgraded to the digital cellular mobile communication (IS-95).
FIG. 1 is a block diagram of a typical wireless communication transceiver. As shown in this drawing, the typical wireless communication transceiver is composed of a BaseBand (BB) modem 100 that performs modulation and demodulation using modulation and demodulation schemes defined by the physical layer specifications of each standard, a Radio Frequency (RF) front-end block (or RF/analog block) 105 that converts a digital modulated signal, output from the modem 100, into an RF modulated signal and converts an RF modulated signal, received from an antenna 110, into a digital modulated signal, and the antenna 110 that wirelessly transmits and receives the RF modulated signals.
In the transmission operation of the RF front-end block 105, a Digital-Analog Converter (DAC) 115 converts a signal, digitally modulated by the modem 100, into an BB analog modulated signal according to bit resolution corresponding to a selected standard, and a Direct Current (DC) component correction and Low-Pass Filter (LPF) unit 120 removes a DC offset from the analog modulated signal output from the DAC 115, and low-pass-filters the analog modulated signal to a bandwidth corresponding to a selected transmission standard.
Frequency up converters 125 and 130 up-convert the In-phase (I) component of the BB analog modulated signal, output from the DC component correction and LPF unit 120, and the Quadrature (Q) component thereof into an RF band corresponding to the selected transmission standard, and output I and Q RF modulated signal components, respectively. The I and Q RF modulated signal components are combined together by an adder 135, and the RF modulated signal output from the adder 135, is amplified by a power amplifier 140.
The RF modulated signal is output to the antenna 110 at transmission periods based on TDD through a transmission/reception switch (T/R SW) 145. In this case, the RF modulated signal passes through a Band-Pass Filter (BPF) 150 to allow an out-of-band spurious signal to be removed therefrom.
In the reception operation of the RF front-end block 105, the RF modulated signal, input from the antenna 110, is freed from an out-of-band spurious signal by the BPF 150, and is input to the transmission/reception switch 145.
The transmission/reception switch 145 outputs the RF modulated signal, output from the power amplifier 140 of a transmission side, toward the antenna 110 through the BPF 150 at the intervals of TDD transmission, or inputs the RF modulated signal, received from the antenna 110 and passed through the BPF 150, to the Low Noise Amplifier (LNA) 170 of a reception side at the intervals of TDD reception.
The LNA 170 low-noise-amplifies the RF modulated signal, output from the T/R SW 145, in an RF frequency band. The low-noise-amplified signal is down-converted into baseband (BB) modulated signals by frequency down conversion mixers 175 and 180 with respect to the I and Q components thereof. A low-pass filter and programmable gain amplifier 185 low-pass-filters the BB modulated signal to a channel bandwidth corresponding to the transmission standard and performs BB amplification with respect to the I and Q components.
An Analog-Digital Converter (ADC) 190 converts the above-described BB modulated signal into a digital modulated signal according to a bit resolution corresponding to the selected transmission standard, and outputs the digital modulated signal to the BB modem 100.
In regard to the generation of a carrier, a programmable divider 160 divides a local oscillation frequency generated by an oscillator 155, and a frequency synthesizer 165 generates a carrier frequency using a frequency output from the programmable divider 160.
In the above-described single standard transceiver, it is possible to design a multi-standard transceiver by combining together transceiver structures for supporting respective standards in parallel. However, in this case, it is difficult to meet costs, area and power consumption requirements demanded by a variety of applications. That is, the method of merely integrating a plurality of single standard transceivers into a system causes the increase of the implementation size and significant power consumption attributable to the duplication of functional blocks, so that it is not easy in terms of product competiveness to adopt the method.